BACKGROUND:
The American Association for the Study of Liver Diseases (AASLD) practice guidelines provide recommendations in diagnosing and managing patients with liver disease from available scientific evidence in combination with expert consensus opinions.

AIM:
To systematically review the evolution of recommendations from AASLD guidelines and identify gaps limiting the evidence-based foundations of these guidelines.

METHODS:
Initial and current AASLD guidelines published from January 1998 to August 2012 were reviewed. The AGREE II instrument was used to evaluate rigour and transparency of guideline development. The number of recommendations, distribution of grades (strength or certainty), classes (benefit versus risk) and types of recommendations were evaluated. Whenever possible, multiple versions were evaluated for evolving scientific evidence.

RESULTS:
A total of 991 recommendations from 28 guidelines on 17 topics were evaluated. From initial to current guidelines, the total number of recommendations increased by 36%(512 to 699). The largest increases were from chronic hepatitis B (HBV) (+71), liver transplantation (+53) and autoimmune hepatitis (AIH) (+27). Most current recommendations are grade II (44%) and less than 20% are grade I. The AGREE II evaluation showed global improvement in guideline quality. Both HBV and chronic hepatitis C guidelines had greatest increases in grade I recommendations (+383% and +67%, respectively). The greatest increases in treatment recommendations were from HBV (grade I, +1150%), liver transplantation (grade II, +112%) and AIH (grade III, +105%).

CONCLUSIONS:
Despite significant increases in the numbers of recommendations within AASLD practice guidelines over time, only a minority are supported by grade I evidence, highlighting the need for developing well-designed investigations to provide evidence for areas of uncertainty and improving the quality of future guidelines in hepatobiliary diseases. (HEPATOLOGY 2013.).